When a Start Event is not used, then all Flow Objects that do not have an incoming Sequence Flow SHALL be the start of a separate parallel path.

Each path will have a separate unique token that will traverse the Sequence Flow.

Message Flow Connections

NOTE: All Message Flows MUST connect two separate Pools. They MAY connect to the Pool boundary or to Flow Objects within the Pool boundary. They MUST NOT connect two objects within the same Pool.

See “Message Flow Connection Rules” on page 41 for the entire set of objects and how they MAY be a source or targets of a Message Flow.

A Start Event MAY be the target for a Message Flow; it can have zero (0) or more incoming Message Flows. Each Message Flow targeting a Start Event represents an instantiation mechanism (a trigger) for the Process. Only one of the triggers is REQUIRED to start a new Process.

A Start Event MUST NOT be a source for a Message Flow; it MUST NOT have outgoing Message Flows.

10.5.3 End Event

As the name implies, the End Event indicates where a Process will end. In terms of Sequence Flows, the End Event ends the flow of the Process, and thus, will not have any outgoing Sequence Flows—no Sequence Flow can connect from an End Event.

The End Event shares the same basic shape of the Start Event and Intermediate Event, a circle with an open center so that markers can be placed within the circle to indicate variations of the Event.

An End Event is a circle that MUST be drawn with a single thick line (see Figure 10.71).

The use of text, color, size, and lines for an End Event MUST follow the rules defined in “Use of Text, Color, Size, and Lines in a Diagram” on page 39 with the exception that:

The thickness of the line MUST remain thick so that the End Event can be distinguished from the Intermediate and Start Events.

Figure 10.71 – End Event

To continue discussing how flow proceeds throughout the Process, an End Event consumes a token that had been generated from a Start Event within the same level of Process. If parallel Sequence Flows targets the End Event, then the tokens will be consumed as they arrive. All the tokens that were generated within the Process MUST be consumed by an End Event before the Process has been completed. In other circumstances, if the Process is a SubProcess, it can be stopped prior to normal completion through interrupting Intermediate Events (See 10.2.2, “exception flow,” on page 274 for more details). In this situation the tokens will be consumed by an Intermediate Event attached to the boundary of the Sub-Process.

Semantics of the End Event include:

There MAY be multiple End Events within a single level of a Process.

An End Event is OPTIONAL: a given Process level—a Process or an expanded Sub-Process—MAY (is NOT REQUIRED to) have this shape:

If an End Event is not used, then the implicit End Event for the Process SHALL NOT have a Result. If there is a Start Event, then there MUST be at least one End Event.

If the End Event is not used, then all Flow Objects that do not have any outgoing Sequence Flow (i.e., are not a source of a Sequence Flow) mark the end of a path in the Process. However, the Process MUST NOT end until all parallel paths have completed.

NOTE: A Process MAY have more than one Process level (i.e., it can include Expanded Sub-Processes or a Call Activity that call other Processes). The use of Start and End Events is independent for each level of the Diagram.

For Processes without an End Event, a token entering a path-ending Flow Object will be consumed when the processing performed by the object is completed (i.e., when the path has completed), as if the token had then gone on to reach an End Event. When all tokens for a given instance of the Process are consumed, then the Process will reach a state of being completed.

End Event Results

There are nine types of End Events in BPMN: None, Message, Escalation, Error, Cancel, Compensation,

Signal, Terminate, and Multiple. These types define the consequence of reaching an End Event. This will be referred to as the End Event Result.

Table 10.88 – End Event Types

Table 10.88 – End Event Types